1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/heapRegionRemSet.hpp"
30 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/space.inline.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "utilities/bitMap.inline.hpp"
35 #include "utilities/globalDefinitions.hpp"
36
37 class PerRegionTable: public CHeapObj<mtGC> {
38 friend class OtherRegionsTable;
39 friend class HeapRegionRemSetIterator;
40
41 HeapRegion* _hr;
42 BitMap _bm;
43 jint _occupied;
44
45 // next pointer for free/allocated 'all' list
46 PerRegionTable* _next;
47
48 // prev pointer for the allocated 'all' list
49 PerRegionTable* _prev;
50
51 // next pointer in collision list
52 PerRegionTable * _collision_list_next;
53
54 // Global free list of PRTs
55 static PerRegionTable* _free_list;
56
57 protected:
58 // We need access in order to union things into the base table.
59 BitMap* bm() { return &_bm; }
60
61 void recount_occupied() {
62 _occupied = (jint) bm()->count_one_bits();
63 }
64
65 PerRegionTable(HeapRegion* hr) :
66 _hr(hr),
67 _occupied(0),
68 _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
69 _collision_list_next(NULL), _next(NULL), _prev(NULL)
70 {}
71
72 void add_card_work(CardIdx_t from_card, bool par) {
73 if (!_bm.at(from_card)) {
74 if (par) {
75 if (_bm.par_at_put(from_card, 1)) {
76 Atomic::inc(&_occupied);
77 }
78 } else {
79 _bm.at_put(from_card, 1);
80 _occupied++;
81 }
82 }
83 }
84
85 void add_reference_work(OopOrNarrowOopStar from, bool par) {
86 // Must make this robust in case "from" is not in "_hr", because of
87 // concurrency.
88
89 if (G1TraceHeapRegionRememberedSet) {
90 gclog_or_tty->print_cr(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT").",
91 from,
92 UseCompressedOops
93 ? oopDesc::load_decode_heap_oop((narrowOop*)from)
94 : oopDesc::load_decode_heap_oop((oop*)from));
95 }
96
97 HeapRegion* loc_hr = hr();
98 // If the test below fails, then this table was reused concurrently
99 // with this operation. This is OK, since the old table was coarsened,
100 // and adding a bit to the new table is never incorrect.
101 // If the table used to belong to a continues humongous region and is
102 // now reused for the corresponding start humongous region, we need to
103 // make sure that we detect this. Thus, we call is_in_reserved_raw()
104 // instead of just is_in_reserved() here.
105 if (loc_hr->is_in_reserved_raw(from)) {
106 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
107 CardIdx_t from_card = (CardIdx_t)
108 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
109
110 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
111 "Must be in range.");
112 add_card_work(from_card, par);
113 }
114 }
115
116 public:
117
118 HeapRegion* hr() const { return _hr; }
119
120 jint occupied() const {
121 // Overkill, but if we ever need it...
122 // guarantee(_occupied == _bm.count_one_bits(), "Check");
123 return _occupied;
124 }
125
126 void init(HeapRegion* hr, bool clear_links_to_all_list) {
127 if (clear_links_to_all_list) {
128 set_next(NULL);
129 set_prev(NULL);
130 }
131 _hr = hr;
132 _collision_list_next = NULL;
133 _occupied = 0;
134 _bm.clear();
135 }
136
137 void add_reference(OopOrNarrowOopStar from) {
138 add_reference_work(from, /*parallel*/ true);
139 }
140
141 void seq_add_reference(OopOrNarrowOopStar from) {
142 add_reference_work(from, /*parallel*/ false);
143 }
144
145 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
146 HeapWord* hr_bot = hr()->bottom();
147 size_t hr_first_card_index = ctbs->index_for(hr_bot);
148 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
149 recount_occupied();
150 }
151
152 void add_card(CardIdx_t from_card_index) {
153 add_card_work(from_card_index, /*parallel*/ true);
154 }
155
156 void seq_add_card(CardIdx_t from_card_index) {
157 add_card_work(from_card_index, /*parallel*/ false);
158 }
159
160 // (Destructively) union the bitmap of the current table into the given
161 // bitmap (which is assumed to be of the same size.)
162 void union_bitmap_into(BitMap* bm) {
163 bm->set_union(_bm);
164 }
165
166 // Mem size in bytes.
167 size_t mem_size() const {
168 return sizeof(this) + _bm.size_in_words() * HeapWordSize;
169 }
170
171 // Requires "from" to be in "hr()".
172 bool contains_reference(OopOrNarrowOopStar from) const {
173 assert(hr()->is_in_reserved(from), "Precondition.");
174 size_t card_ind = pointer_delta(from, hr()->bottom(),
175 CardTableModRefBS::card_size);
176 return _bm.at(card_ind);
177 }
178
179 // Bulk-free the PRTs from prt to last, assumes that they are
180 // linked together using their _next field.
181 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
182 while (true) {
183 PerRegionTable* fl = _free_list;
184 last->set_next(fl);
185 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
186 if (res == fl) {
187 return;
188 }
189 }
190 ShouldNotReachHere();
191 }
192
193 static void free(PerRegionTable* prt) {
194 bulk_free(prt, prt);
195 }
196
197 // Returns an initialized PerRegionTable instance.
198 static PerRegionTable* alloc(HeapRegion* hr) {
199 PerRegionTable* fl = _free_list;
200 while (fl != NULL) {
201 PerRegionTable* nxt = fl->next();
202 PerRegionTable* res =
203 (PerRegionTable*)
204 Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
205 if (res == fl) {
206 fl->init(hr, true);
207 return fl;
208 } else {
209 fl = _free_list;
210 }
211 }
212 assert(fl == NULL, "Loop condition.");
213 return new PerRegionTable(hr);
214 }
215
216 PerRegionTable* next() const { return _next; }
217 void set_next(PerRegionTable* next) { _next = next; }
218 PerRegionTable* prev() const { return _prev; }
219 void set_prev(PerRegionTable* prev) { _prev = prev; }
220
221 // Accessor and Modification routines for the pointer for the
222 // singly linked collision list that links the PRTs within the
223 // OtherRegionsTable::_fine_grain_regions hash table.
224 //
225 // It might be useful to also make the collision list doubly linked
226 // to avoid iteration over the collisions list during scrubbing/deletion.
227 // OTOH there might not be many collisions.
228
229 PerRegionTable* collision_list_next() const {
230 return _collision_list_next;
231 }
232
233 void set_collision_list_next(PerRegionTable* next) {
234 _collision_list_next = next;
235 }
236
237 PerRegionTable** collision_list_next_addr() {
238 return &_collision_list_next;
239 }
240
241 static size_t fl_mem_size() {
242 PerRegionTable* cur = _free_list;
243 size_t res = 0;
244 while (cur != NULL) {
245 res += sizeof(PerRegionTable);
246 cur = cur->next();
247 }
248 return res;
249 }
250 };
251
252 PerRegionTable* PerRegionTable::_free_list = NULL;
253
254 size_t OtherRegionsTable::_max_fine_entries = 0;
255 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
256 size_t OtherRegionsTable::_fine_eviction_stride = 0;
257 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
258
259 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr) :
260 _g1h(G1CollectedHeap::heap()),
261 _m(Mutex::leaf, "An OtherRegionsTable lock", true),
262 _hr(hr),
263 _coarse_map(G1CollectedHeap::heap()->max_regions(),
264 false /* in-resource-area */),
265 _fine_grain_regions(NULL),
266 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
267 _n_fine_entries(0), _n_coarse_entries(0),
268 _fine_eviction_start(0),
269 _sparse_table(hr)
270 {
271 typedef PerRegionTable* PerRegionTablePtr;
272
273 if (_max_fine_entries == 0) {
274 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
275 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
276 _max_fine_entries = (size_t)1 << max_entries_log;
277 _mod_max_fine_entries_mask = _max_fine_entries - 1;
278
279 assert(_fine_eviction_sample_size == 0
280 && _fine_eviction_stride == 0, "All init at same time.");
281 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
282 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
283 }
284
285 _fine_grain_regions = new PerRegionTablePtr[_max_fine_entries];
286
287 if (_fine_grain_regions == NULL) {
288 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
289 "Failed to allocate _fine_grain_entries.");
290 }
291
292 for (size_t i = 0; i < _max_fine_entries; i++) {
293 _fine_grain_regions[i] = NULL;
294 }
295 }
296
297 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
298 // We always append to the beginning of the list for convenience;
299 // the order of entries in this list does not matter.
300 if (_first_all_fine_prts != NULL) {
301 assert(_first_all_fine_prts->prev() == NULL, "invariant");
302 _first_all_fine_prts->set_prev(prt);
303 prt->set_next(_first_all_fine_prts);
304 } else {
305 // this is the first element we insert. Adjust the "last" pointer
306 _last_all_fine_prts = prt;
307 assert(prt->next() == NULL, "just checking");
308 }
309 // the new element is always the first element without a predecessor
310 prt->set_prev(NULL);
311 _first_all_fine_prts = prt;
312
313 assert(prt->prev() == NULL, "just checking");
314 assert(_first_all_fine_prts == prt, "just checking");
315 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
316 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
317 "just checking");
318 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
319 "just checking");
320 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
321 "just checking");
322 }
323
324 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
325 if (prt->prev() != NULL) {
326 assert(_first_all_fine_prts != prt, "just checking");
327 prt->prev()->set_next(prt->next());
328 // removing the last element in the list?
329 if (_last_all_fine_prts == prt) {
330 _last_all_fine_prts = prt->prev();
331 }
332 } else {
333 assert(_first_all_fine_prts == prt, "just checking");
334 _first_all_fine_prts = prt->next();
335 // list is empty now?
336 if (_first_all_fine_prts == NULL) {
337 _last_all_fine_prts = NULL;
338 }
339 }
340
341 if (prt->next() != NULL) {
342 prt->next()->set_prev(prt->prev());
343 }
344
345 prt->set_next(NULL);
346 prt->set_prev(NULL);
347
348 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
349 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
350 "just checking");
351 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
352 "just checking");
353 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
354 "just checking");
355 }
356
357 int** OtherRegionsTable::_from_card_cache = NULL;
358 size_t OtherRegionsTable::_from_card_cache_max_regions = 0;
359 size_t OtherRegionsTable::_from_card_cache_mem_size = 0;
360
361 void OtherRegionsTable::init_from_card_cache(size_t max_regions) {
362 _from_card_cache_max_regions = max_regions;
363
364 int n_par_rs = HeapRegionRemSet::num_par_rem_sets();
365 _from_card_cache = NEW_C_HEAP_ARRAY(int*, n_par_rs, mtGC);
366 for (int i = 0; i < n_par_rs; i++) {
367 _from_card_cache[i] = NEW_C_HEAP_ARRAY(int, max_regions, mtGC);
368 for (size_t j = 0; j < max_regions; j++) {
369 _from_card_cache[i][j] = -1; // An invalid value.
370 }
371 }
372 _from_card_cache_mem_size = n_par_rs * max_regions * sizeof(int);
373 }
374
375 void OtherRegionsTable::shrink_from_card_cache(size_t new_n_regs) {
376 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
377 assert(new_n_regs <= _from_card_cache_max_regions, "Must be within max.");
378 for (size_t j = new_n_regs; j < _from_card_cache_max_regions; j++) {
379 _from_card_cache[i][j] = -1; // An invalid value.
380 }
381 }
382 }
383
384 #ifndef PRODUCT
385 void OtherRegionsTable::print_from_card_cache() {
386 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
387 for (size_t j = 0; j < _from_card_cache_max_regions; j++) {
388 gclog_or_tty->print_cr("_from_card_cache[%d][%d] = %d.",
389 i, j, _from_card_cache[i][j]);
390 }
391 }
392 }
393 #endif
394
395 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, int tid) {
396 size_t cur_hrs_ind = (size_t) hr()->hrs_index();
397
398 if (G1TraceHeapRegionRememberedSet) {
399 gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
400 from,
401 UseCompressedOops
402 ? oopDesc::load_decode_heap_oop((narrowOop*)from)
403 : oopDesc::load_decode_heap_oop((oop*)from));
404 }
405
406 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
407
408 if (G1TraceHeapRegionRememberedSet) {
409 gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
410 hr()->bottom(), from_card,
411 _from_card_cache[tid][cur_hrs_ind]);
412 }
413
414 if (from_card == _from_card_cache[tid][cur_hrs_ind]) {
415 if (G1TraceHeapRegionRememberedSet) {
416 gclog_or_tty->print_cr(" from-card cache hit.");
417 }
418 assert(contains_reference(from), "We just added it!");
419 return;
420 } else {
421 _from_card_cache[tid][cur_hrs_ind] = from_card;
422 }
423
424 // Note that this may be a continued H region.
425 HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
426 RegionIdx_t from_hrs_ind = (RegionIdx_t) from_hr->hrs_index();
427
428 // If the region is already coarsened, return.
429 if (_coarse_map.at(from_hrs_ind)) {
430 if (G1TraceHeapRegionRememberedSet) {
431 gclog_or_tty->print_cr(" coarse map hit.");
432 }
433 assert(contains_reference(from), "We just added it!");
434 return;
435 }
436
437 // Otherwise find a per-region table to add it to.
438 size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
439 PerRegionTable* prt = find_region_table(ind, from_hr);
440 if (prt == NULL) {
441 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
442 // Confirm that it's really not there...
443 prt = find_region_table(ind, from_hr);
444 if (prt == NULL) {
445
446 uintptr_t from_hr_bot_card_index =
447 uintptr_t(from_hr->bottom())
448 >> CardTableModRefBS::card_shift;
449 CardIdx_t card_index = from_card - from_hr_bot_card_index;
450 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
451 "Must be in range.");
452 if (G1HRRSUseSparseTable &&
453 _sparse_table.add_card(from_hrs_ind, card_index)) {
454 if (G1RecordHRRSOops) {
455 HeapRegionRemSet::record(hr(), from);
456 if (G1TraceHeapRegionRememberedSet) {
457 gclog_or_tty->print(" Added card " PTR_FORMAT " to region "
458 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
459 align_size_down(uintptr_t(from),
460 CardTableModRefBS::card_size),
461 hr()->bottom(), from);
462 }
463 }
464 if (G1TraceHeapRegionRememberedSet) {
465 gclog_or_tty->print_cr(" added card to sparse table.");
466 }
467 assert(contains_reference_locked(from), "We just added it!");
468 return;
469 } else {
470 if (G1TraceHeapRegionRememberedSet) {
471 gclog_or_tty->print_cr(" [tid %d] sparse table entry "
472 "overflow(f: %d, t: %d)",
473 tid, from_hrs_ind, cur_hrs_ind);
474 }
475 }
476
477 if (_n_fine_entries == _max_fine_entries) {
478 prt = delete_region_table();
479 // There is no need to clear the links to the 'all' list here:
480 // prt will be reused immediately, i.e. remain in the 'all' list.
481 prt->init(from_hr, false /* clear_links_to_all_list */);
482 } else {
483 prt = PerRegionTable::alloc(from_hr);
484 link_to_all(prt);
485 }
486
487 PerRegionTable* first_prt = _fine_grain_regions[ind];
488 prt->set_collision_list_next(first_prt);
489 _fine_grain_regions[ind] = prt;
490 _n_fine_entries++;
491
492 if (G1HRRSUseSparseTable) {
493 // Transfer from sparse to fine-grain.
494 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrs_ind);
495 assert(sprt_entry != NULL, "There should have been an entry");
496 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
497 CardIdx_t c = sprt_entry->card(i);
498 if (c != SparsePRTEntry::NullEntry) {
499 prt->add_card(c);
500 }
501 }
502 // Now we can delete the sparse entry.
503 bool res = _sparse_table.delete_entry(from_hrs_ind);
504 assert(res, "It should have been there.");
505 }
506 }
507 assert(prt != NULL && prt->hr() == from_hr, "consequence");
508 }
509 // Note that we can't assert "prt->hr() == from_hr", because of the
510 // possibility of concurrent reuse. But see head comment of
511 // OtherRegionsTable for why this is OK.
512 assert(prt != NULL, "Inv");
513
514 prt->add_reference(from);
515
516 if (G1RecordHRRSOops) {
517 HeapRegionRemSet::record(hr(), from);
518 if (G1TraceHeapRegionRememberedSet) {
519 gclog_or_tty->print("Added card " PTR_FORMAT " to region "
520 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
521 align_size_down(uintptr_t(from),
522 CardTableModRefBS::card_size),
523 hr()->bottom(), from);
524 }
525 }
526 assert(contains_reference(from), "We just added it!");
527 }
528
529 PerRegionTable*
530 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
531 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
532 PerRegionTable* prt = _fine_grain_regions[ind];
533 while (prt != NULL && prt->hr() != hr) {
534 prt = prt->collision_list_next();
535 }
536 // Loop postcondition is the method postcondition.
537 return prt;
538 }
539
540 jint OtherRegionsTable::_n_coarsenings = 0;
541
542 PerRegionTable* OtherRegionsTable::delete_region_table() {
543 assert(_m.owned_by_self(), "Precondition");
544 assert(_n_fine_entries == _max_fine_entries, "Precondition");
545 PerRegionTable* max = NULL;
546 jint max_occ = 0;
547 PerRegionTable** max_prev;
548 size_t max_ind;
549
550 size_t i = _fine_eviction_start;
551 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
552 size_t ii = i;
553 // Make sure we get a non-NULL sample.
554 while (_fine_grain_regions[ii] == NULL) {
555 ii++;
556 if (ii == _max_fine_entries) ii = 0;
557 guarantee(ii != i, "We must find one.");
558 }
559 PerRegionTable** prev = &_fine_grain_regions[ii];
560 PerRegionTable* cur = *prev;
561 while (cur != NULL) {
562 jint cur_occ = cur->occupied();
563 if (max == NULL || cur_occ > max_occ) {
564 max = cur;
565 max_prev = prev;
566 max_ind = i;
567 max_occ = cur_occ;
568 }
569 prev = cur->collision_list_next_addr();
570 cur = cur->collision_list_next();
571 }
572 i = i + _fine_eviction_stride;
573 if (i >= _n_fine_entries) i = i - _n_fine_entries;
574 }
575
576 _fine_eviction_start++;
577
578 if (_fine_eviction_start >= _n_fine_entries) {
579 _fine_eviction_start -= _n_fine_entries;
580 }
581
582 guarantee(max != NULL, "Since _n_fine_entries > 0");
583
584 // Set the corresponding coarse bit.
585 size_t max_hrs_index = (size_t) max->hr()->hrs_index();
586 if (!_coarse_map.at(max_hrs_index)) {
587 _coarse_map.at_put(max_hrs_index, true);
588 _n_coarse_entries++;
589 if (G1TraceHeapRegionRememberedSet) {
590 gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
591 "for region [" PTR_FORMAT "...] (%d coarse entries).\n",
592 hr()->bottom(),
593 max->hr()->bottom(),
594 _n_coarse_entries);
595 }
596 }
597
598 // Unsplice.
599 *max_prev = max->collision_list_next();
600 Atomic::inc(&_n_coarsenings);
601 _n_fine_entries--;
602 return max;
603 }
604
605
606 // At present, this must be called stop-world single-threaded.
607 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
608 BitMap* region_bm, BitMap* card_bm) {
609 // First eliminated garbage regions from the coarse map.
610 if (G1RSScrubVerbose) {
611 gclog_or_tty->print_cr("Scrubbing region %u:", hr()->hrs_index());
612 }
613
614 assert(_coarse_map.size() == region_bm->size(), "Precondition");
615 if (G1RSScrubVerbose) {
616 gclog_or_tty->print(" Coarse map: before = "SIZE_FORMAT"...",
617 _n_coarse_entries);
618 }
619 _coarse_map.set_intersection(*region_bm);
620 _n_coarse_entries = _coarse_map.count_one_bits();
621 if (G1RSScrubVerbose) {
622 gclog_or_tty->print_cr(" after = "SIZE_FORMAT".", _n_coarse_entries);
623 }
624
625 // Now do the fine-grained maps.
626 for (size_t i = 0; i < _max_fine_entries; i++) {
627 PerRegionTable* cur = _fine_grain_regions[i];
628 PerRegionTable** prev = &_fine_grain_regions[i];
629 while (cur != NULL) {
630 PerRegionTable* nxt = cur->collision_list_next();
631 // If the entire region is dead, eliminate.
632 if (G1RSScrubVerbose) {
633 gclog_or_tty->print_cr(" For other region %u:",
634 cur->hr()->hrs_index());
635 }
636 if (!region_bm->at((size_t) cur->hr()->hrs_index())) {
637 *prev = nxt;
638 cur->set_collision_list_next(NULL);
639 _n_fine_entries--;
640 if (G1RSScrubVerbose) {
641 gclog_or_tty->print_cr(" deleted via region map.");
642 }
643 unlink_from_all(cur);
644 PerRegionTable::free(cur);
645 } else {
646 // Do fine-grain elimination.
647 if (G1RSScrubVerbose) {
648 gclog_or_tty->print(" occ: before = %4d.", cur->occupied());
649 }
650 cur->scrub(ctbs, card_bm);
651 if (G1RSScrubVerbose) {
652 gclog_or_tty->print_cr(" after = %4d.", cur->occupied());
653 }
654 // Did that empty the table completely?
655 if (cur->occupied() == 0) {
656 *prev = nxt;
657 cur->set_collision_list_next(NULL);
658 _n_fine_entries--;
659 unlink_from_all(cur);
660 PerRegionTable::free(cur);
661 } else {
662 prev = cur->collision_list_next_addr();
663 }
664 }
665 cur = nxt;
666 }
667 }
668 // Since we may have deleted a from_card_cache entry from the RS, clear
669 // the FCC.
670 clear_fcc();
671 }
672
673
674 size_t OtherRegionsTable::occupied() const {
675 // Cast away const in this case.
676 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
677 size_t sum = occ_fine();
678 sum += occ_sparse();
679 sum += occ_coarse();
680 return sum;
681 }
682
683 size_t OtherRegionsTable::occ_fine() const {
684 size_t sum = 0;
685
686 size_t num = 0;
687 PerRegionTable * cur = _first_all_fine_prts;
688 while (cur != NULL) {
689 sum += cur->occupied();
690 cur = cur->next();
691 num++;
692 }
693 guarantee(num == _n_fine_entries, "just checking");
694 return sum;
695 }
696
697 size_t OtherRegionsTable::occ_coarse() const {
698 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
699 }
700
701 size_t OtherRegionsTable::occ_sparse() const {
702 return _sparse_table.occupied();
703 }
704
705 size_t OtherRegionsTable::mem_size() const {
706 // Cast away const in this case.
707 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
708 size_t sum = 0;
709 PerRegionTable * cur = _first_all_fine_prts;
710 while (cur != NULL) {
711 sum += cur->mem_size();
712 cur = cur->next();
713 }
714 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
715 sum += (_coarse_map.size_in_words() * HeapWordSize);
716 sum += (_sparse_table.mem_size());
717 sum += sizeof(*this) - sizeof(_sparse_table); // Avoid double counting above.
718 return sum;
719 }
720
721 size_t OtherRegionsTable::static_mem_size() {
722 return _from_card_cache_mem_size;
723 }
724
725 size_t OtherRegionsTable::fl_mem_size() {
726 return PerRegionTable::fl_mem_size();
727 }
728
729 void OtherRegionsTable::clear_fcc() {
730 size_t hrs_idx = hr()->hrs_index();
731 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
732 _from_card_cache[i][hrs_idx] = -1;
733 }
734 }
735
736 void OtherRegionsTable::clear() {
737 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
738 // if there are no entries, skip this step
739 if (_first_all_fine_prts != NULL) {
740 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
741 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
742 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
743 } else {
744 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
745 }
746
747 _first_all_fine_prts = _last_all_fine_prts = NULL;
748 _sparse_table.clear();
749 _coarse_map.clear();
750 _n_fine_entries = 0;
751 _n_coarse_entries = 0;
752
753 clear_fcc();
754 }
755
756 void OtherRegionsTable::clear_incoming_entry(HeapRegion* from_hr) {
757 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
758 size_t hrs_ind = (size_t) from_hr->hrs_index();
759 size_t ind = hrs_ind & _mod_max_fine_entries_mask;
760 if (del_single_region_table(ind, from_hr)) {
761 assert(!_coarse_map.at(hrs_ind), "Inv");
762 } else {
763 _coarse_map.par_at_put(hrs_ind, 0);
764 }
765 // Check to see if any of the fcc entries come from here.
766 size_t hr_ind = (size_t) hr()->hrs_index();
767 for (int tid = 0; tid < HeapRegionRemSet::num_par_rem_sets(); tid++) {
768 int fcc_ent = _from_card_cache[tid][hr_ind];
769 if (fcc_ent != -1) {
770 HeapWord* card_addr = (HeapWord*)
771 (uintptr_t(fcc_ent) << CardTableModRefBS::card_shift);
772 if (hr()->is_in_reserved(card_addr)) {
773 // Clear the from card cache.
774 _from_card_cache[tid][hr_ind] = -1;
775 }
776 }
777 }
778 }
779
780 bool OtherRegionsTable::del_single_region_table(size_t ind,
781 HeapRegion* hr) {
782 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
783 PerRegionTable** prev_addr = &_fine_grain_regions[ind];
784 PerRegionTable* prt = *prev_addr;
785 while (prt != NULL && prt->hr() != hr) {
786 prev_addr = prt->collision_list_next_addr();
787 prt = prt->collision_list_next();
788 }
789 if (prt != NULL) {
790 assert(prt->hr() == hr, "Loop postcondition.");
791 *prev_addr = prt->collision_list_next();
792 unlink_from_all(prt);
793 PerRegionTable::free(prt);
794 _n_fine_entries--;
795 return true;
796 } else {
797 return false;
798 }
799 }
800
801 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
802 // Cast away const in this case.
803 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
804 return contains_reference_locked(from);
805 }
806
807 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
808 HeapRegion* hr = _g1h->heap_region_containing_raw(from);
809 if (hr == NULL) return false;
810 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrs_index();
811 // Is this region in the coarse map?
812 if (_coarse_map.at(hr_ind)) return true;
813
814 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
815 hr);
816 if (prt != NULL) {
817 return prt->contains_reference(from);
818
819 } else {
820 uintptr_t from_card =
821 (uintptr_t(from) >> CardTableModRefBS::card_shift);
822 uintptr_t hr_bot_card_index =
823 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
824 assert(from_card >= hr_bot_card_index, "Inv");
825 CardIdx_t card_index = from_card - hr_bot_card_index;
826 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
827 "Must be in range.");
828 return _sparse_table.contains_card(hr_ind, card_index);
829 }
830
831
832 }
833
834 void
835 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
836 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
837 }
838
839 // Determines how many threads can add records to an rset in parallel.
840 // This can be done by either mutator threads together with the
841 // concurrent refinement threads or GC threads.
842 int HeapRegionRemSet::num_par_rem_sets() {
843 return (int)MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
844 }
845
846 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
847 HeapRegion* hr)
848 : _bosa(bosa), _other_regions(hr) {
849 reset_for_par_iteration();
850 }
851
852 void HeapRegionRemSet::setup_remset_size() {
853 // Setup sparse and fine-grain tables sizes.
854 // table_size = base * (log(region_size / 1M) + 1)
855 const int LOG_M = 20;
856 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
857 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
858 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
859 }
860 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
861 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
862 }
863 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
864 }
865
866 bool HeapRegionRemSet::claim_iter() {
867 if (_iter_state != Unclaimed) return false;
868 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
869 return (res == Unclaimed);
870 }
871
872 void HeapRegionRemSet::set_iter_complete() {
873 _iter_state = Complete;
874 }
875
876 bool HeapRegionRemSet::iter_is_complete() {
877 return _iter_state == Complete;
878 }
879
880 #ifndef PRODUCT
881 void HeapRegionRemSet::print() const {
882 HeapRegionRemSetIterator iter(this);
883 size_t card_index;
884 while (iter.has_next(card_index)) {
885 HeapWord* card_start =
886 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
887 gclog_or_tty->print_cr(" Card " PTR_FORMAT, card_start);
888 }
889 if (iter.n_yielded() != occupied()) {
890 gclog_or_tty->print_cr("Yielded disagrees with occupied:");
891 gclog_or_tty->print_cr(" %6d yielded (%6d coarse, %6d fine).",
892 iter.n_yielded(),
893 iter.n_yielded_coarse(), iter.n_yielded_fine());
894 gclog_or_tty->print_cr(" %6d occ (%6d coarse, %6d fine).",
895 occupied(), occ_coarse(), occ_fine());
896 }
897 guarantee(iter.n_yielded() == occupied(),
898 "We should have yielded all the represented cards.");
899 }
900 #endif
901
902 void HeapRegionRemSet::cleanup() {
903 SparsePRT::cleanup_all();
904 }
905
906 void HeapRegionRemSet::clear() {
907 _other_regions.clear();
908 assert(occupied() == 0, "Should be clear.");
909 reset_for_par_iteration();
910 }
911
912 void HeapRegionRemSet::reset_for_par_iteration() {
913 _iter_state = Unclaimed;
914 _iter_claimed = 0;
915 // It's good to check this to make sure that the two methods are in sync.
916 assert(verify_ready_for_par_iteration(), "post-condition");
917 }
918
919 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
920 BitMap* region_bm, BitMap* card_bm) {
921 _other_regions.scrub(ctbs, region_bm, card_bm);
922 }
923
924 //-------------------- Iteration --------------------
925
926 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(const HeapRegionRemSet* hrrs) :
927 _hrrs(hrrs),
928 _g1h(G1CollectedHeap::heap()),
929 _coarse_map(&hrrs->_other_regions._coarse_map),
930 _fine_grain_regions(hrrs->_other_regions._fine_grain_regions),
931 _bosa(hrrs->bosa()),
932 _is(Sparse),
933 // Set these values so that we increment to the first region.
934 _coarse_cur_region_index(-1),
935 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
936 _cur_region_cur_card(0),
937 _fine_array_index(-1),
938 _fine_cur_prt(NULL),
939 _n_yielded_coarse(0),
940 _n_yielded_fine(0),
941 _n_yielded_sparse(0),
942 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
943
944 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
945 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
946 // Go to the next card.
947 _coarse_cur_region_cur_card++;
948 // Was the last the last card in the current region?
949 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
950 // Yes: find the next region. This may leave _coarse_cur_region_index
951 // Set to the last index, in which case there are no more coarse
952 // regions.
953 _coarse_cur_region_index =
954 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
955 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
956 _coarse_cur_region_cur_card = 0;
957 HeapWord* r_bot =
958 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
959 _cur_region_card_offset = _bosa->index_for(r_bot);
960 } else {
961 return false;
962 }
963 }
964 // If we didn't return false above, then we can yield a card.
965 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
966 return true;
967 }
968
969 void HeapRegionRemSetIterator::fine_find_next_non_null_prt() {
970 // Otherwise, find the next bucket list in the array.
971 _fine_array_index++;
972 while (_fine_array_index < (int) OtherRegionsTable::_max_fine_entries) {
973 _fine_cur_prt = _fine_grain_regions[_fine_array_index];
974 if (_fine_cur_prt != NULL) return;
975 else _fine_array_index++;
976 }
977 assert(_fine_cur_prt == NULL, "Loop post");
978 }
979
980 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
981 if (fine_has_next()) {
982 _cur_region_cur_card =
983 _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
984 }
985 while (!fine_has_next()) {
986 if (_cur_region_cur_card == (size_t) HeapRegion::CardsPerRegion) {
987 _cur_region_cur_card = 0;
988 _fine_cur_prt = _fine_cur_prt->collision_list_next();
989 }
990 if (_fine_cur_prt == NULL) {
991 fine_find_next_non_null_prt();
992 if (_fine_cur_prt == NULL) return false;
993 }
994 assert(_fine_cur_prt != NULL && _cur_region_cur_card == 0,
995 "inv.");
996 HeapWord* r_bot =
997 _fine_cur_prt->hr()->bottom();
998 _cur_region_card_offset = _bosa->index_for(r_bot);
999 _cur_region_cur_card = _fine_cur_prt->_bm.get_next_one_offset(0);
1000 }
1001 assert(fine_has_next(), "Or else we exited the loop via the return.");
1002 card_index = _cur_region_card_offset + _cur_region_cur_card;
1003 return true;
1004 }
1005
1006 bool HeapRegionRemSetIterator::fine_has_next() {
1007 return
1008 _fine_cur_prt != NULL &&
1009 _cur_region_cur_card < HeapRegion::CardsPerRegion;
1010 }
1011
1012 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1013 switch (_is) {
1014 case Sparse:
1015 if (_sparse_iter.has_next(card_index)) {
1016 _n_yielded_sparse++;
1017 return true;
1018 }
1019 // Otherwise, deliberate fall-through
1020 _is = Fine;
1021 case Fine:
1022 if (fine_has_next(card_index)) {
1023 _n_yielded_fine++;
1024 return true;
1025 }
1026 // Otherwise, deliberate fall-through
1027 _is = Coarse;
1028 case Coarse:
1029 if (coarse_has_next(card_index)) {
1030 _n_yielded_coarse++;
1031 return true;
1032 }
1033 // Otherwise...
1034 break;
1035 }
1036 assert(ParallelGCThreads > 1 ||
1037 n_yielded() == _hrrs->occupied(),
1038 "Should have yielded all the cards in the rem set "
1039 "(in the non-par case).");
1040 return false;
1041 }
1042
1043
1044
1045 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1046 HeapWord** HeapRegionRemSet::_recorded_cards = NULL;
1047 HeapRegion** HeapRegionRemSet::_recorded_regions = NULL;
1048 int HeapRegionRemSet::_n_recorded = 0;
1049
1050 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1051 int* HeapRegionRemSet::_recorded_event_index = NULL;
1052 int HeapRegionRemSet::_n_recorded_events = 0;
1053
1054 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1055 if (_recorded_oops == NULL) {
1056 assert(_n_recorded == 0
1057 && _recorded_cards == NULL
1058 && _recorded_regions == NULL,
1059 "Inv");
1060 _recorded_oops = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1061 _recorded_cards = NEW_C_HEAP_ARRAY(HeapWord*, MaxRecorded, mtGC);
1062 _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*, MaxRecorded, mtGC);
1063 }
1064 if (_n_recorded == MaxRecorded) {
1065 gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1066 } else {
1067 _recorded_cards[_n_recorded] =
1068 (HeapWord*)align_size_down(uintptr_t(f),
1069 CardTableModRefBS::card_size);
1070 _recorded_oops[_n_recorded] = f;
1071 _recorded_regions[_n_recorded] = hr;
1072 _n_recorded++;
1073 }
1074 }
1075
1076 void HeapRegionRemSet::record_event(Event evnt) {
1077 if (!G1RecordHRRSEvents) return;
1078
1079 if (_recorded_events == NULL) {
1080 assert(_n_recorded_events == 0
1081 && _recorded_event_index == NULL,
1082 "Inv");
1083 _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1084 _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1085 }
1086 if (_n_recorded_events == MaxRecordedEvents) {
1087 gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1088 } else {
1089 _recorded_events[_n_recorded_events] = evnt;
1090 _recorded_event_index[_n_recorded_events] = _n_recorded;
1091 _n_recorded_events++;
1092 }
1093 }
1094
1095 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1096 switch (evnt) {
1097 case Event_EvacStart:
1098 str->print("Evac Start");
1099 break;
1100 case Event_EvacEnd:
1101 str->print("Evac End");
1102 break;
1103 case Event_RSUpdateEnd:
1104 str->print("RS Update End");
1105 break;
1106 }
1107 }
1108
1109 void HeapRegionRemSet::print_recorded() {
1110 int cur_evnt = 0;
1111 Event cur_evnt_kind;
1112 int cur_evnt_ind = 0;
1113 if (_n_recorded_events > 0) {
1114 cur_evnt_kind = _recorded_events[cur_evnt];
1115 cur_evnt_ind = _recorded_event_index[cur_evnt];
1116 }
1117
1118 for (int i = 0; i < _n_recorded; i++) {
1119 while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1120 gclog_or_tty->print("Event: ");
1121 print_event(gclog_or_tty, cur_evnt_kind);
1122 gclog_or_tty->print_cr("");
1123 cur_evnt++;
1124 if (cur_evnt < MaxRecordedEvents) {
1125 cur_evnt_kind = _recorded_events[cur_evnt];
1126 cur_evnt_ind = _recorded_event_index[cur_evnt];
1127 }
1128 }
1129 gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1130 " for ref " PTR_FORMAT ".\n",
1131 _recorded_cards[i], _recorded_regions[i]->bottom(),
1132 _recorded_oops[i]);
1133 }
1134 }
1135
1136 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1137 SparsePRT::reset_for_cleanup_tasks();
1138 }
1139
1140 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1141 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1142 }
1143
1144 void
1145 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1146 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1147 }
1148
1149 #ifndef PRODUCT
1150 void HeapRegionRemSet::test() {
1151 os::sleep(Thread::current(), (jlong)5000, false);
1152 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1153
1154 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1155 // hash bucket.
1156 HeapRegion* hr0 = g1h->region_at(0);
1157 HeapRegion* hr1 = g1h->region_at(1);
1158 HeapRegion* hr2 = g1h->region_at(5);
1159 HeapRegion* hr3 = g1h->region_at(6);
1160 HeapRegion* hr4 = g1h->region_at(7);
1161 HeapRegion* hr5 = g1h->region_at(8);
1162
1163 HeapWord* hr1_start = hr1->bottom();
1164 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1165 HeapWord* hr1_last = hr1->end() - 1;
1166
1167 HeapWord* hr2_start = hr2->bottom();
1168 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1169 HeapWord* hr2_last = hr2->end() - 1;
1170
1171 HeapWord* hr3_start = hr3->bottom();
1172 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1173 HeapWord* hr3_last = hr3->end() - 1;
1174
1175 HeapRegionRemSet* hrrs = hr0->rem_set();
1176
1177 // Make three references from region 0x101...
1178 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1179 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1180 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1181
1182 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1183 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1184 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1185
1186 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1187 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1188 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1189
1190 // Now cause a coarsening.
1191 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1192 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1193
1194 // Now, does iteration yield these three?
1195 HeapRegionRemSetIterator iter(hrrs);
1196 size_t sum = 0;
1197 size_t card_index;
1198 while (iter.has_next(card_index)) {
1199 HeapWord* card_start =
1200 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1201 gclog_or_tty->print_cr(" Card " PTR_FORMAT ".", card_start);
1202 sum++;
1203 }
1204 guarantee(sum == 11 - 3 + 2048, "Failure");
1205 guarantee(sum == hrrs->occupied(), "Failure");
1206 }
1207 #endif